1. Field of the Invention
This invention relates to a reinforced construction of bead portions of radial tires for heavy load vehicles such as trucks, buses etc.
2. Description of the Prior Art
An excellent reinforced construction of bead portions of the above mentioned kind of radial tires has heretofore been proposed, for example, in U.S. Pat. No. 4,046,183. In such prior art construction, a carcass ply composed of radially directed metal cords such as steel cords etc., is wrapped around bead cores from the inside toward the outside thereof to form loops and turned-up portions, respectively. These loops and turned-up portions are secured to bead portions. On the outside of the turned-up portion are laid in bias at least two organic fiber cord layers formed of nylon etc. Between these two organic cord layers is interposed at least one metal cord layer formed of steel etc., the metal cord being inclined to and crossed with respect to a radially directed surface of the tire.
The tire constructed as above described has been favorably accepted by drivers as a tire which can be used under severe and heavy load condition. Recently, some drivers have begun to use such tires under more even severe conditions due to economic conditions such that as a result, bead separation failure is sometimes induced. On the one hand, in order to substantially reduce the cost of tires, the rate of using a steel cord radial tire as a recapped tire has increased. It has become the present tendency to recap a worn tire two or three times. Under such circumstances, it is vigorously desired to eliminate bead separation failure which is vital to preserving a base tire, and hence it is desirable to provide a highly durable reinforced bead construction.